immunogenesi

Immunogenesis, or the generation of an immune response, is the collective process by which an organism recognizes an antigen and mounts an adaptive immune reaction. The term covers the sequence from initial antigen recognition and innate sensing to the activation and differentiation of antigen-specific lymphocytes, formation of effector cells that eliminate the threat, and the development of immunological memory that provides future protection.

Key events include antigen presentation and co-stimulation. Dendritic cells and other antigen-presenting cells capture foreign material, migrate to draining lymph nodes, and present peptide fragments on MHC molecules to naive T cells. B cells can recognize native antigen via B cell receptors and, with help from helper T cells, undergo activation, class-switch recombination, and affinity maturation in germinal centers, leading to high-affinity antibodies.

Effector responses follow: cytotoxic T cells destroy infected cells; helper T cells coordinate responses; plasma cells secrete antibodies that neutralize pathogens and facilitate clearance. Memory B and T cells persist after the initial response, enabling quicker and stronger responses on re-exposure.

Factors that influence immunogenesis include intrinsic properties of the immunogen, such as size, complexity, epitope density, and whether it is a hapten. Adjuvants, route of exposure, prior immunity, age, and genetic background also shape the magnitude and quality of the response. Understanding immunogenesis is central to vaccine design, immunotherapy, and managing hypersensitivity or autoimmune conditions.